Renormalon-motivated evaluation of QCD observables

Abstract

A method of evaluation of spacelike QCD observables D(Q2) is developed, motivated by the renormalon structure of these quantities. A related auxiliary quantity D(Q2) is introduced, which is renomalization scale independent only at the one-loop level, and a large-β0-type renormalon motivated Ansatz is made for the Borel transform of this quantity. This leads to a "dressed" Borel transform of the considered observable D(Q2). Subsequently, a Neubert-type distribution is obtained for the observable. The described method is then applied to the massless Adler function and the related decay ratio of the τ lepton semihadronic decays. Comparisons are then made with an evaluation method at higher truncated orders, developed in our earlier works, which is a renormalization scale invariant extension of the diagonal Padé approximants.